Hal, What we are missing is an industry standard SQL-DDL schema specification. What XML Spy is doing does not even attempt to address that problem. In this example they have defined a FLIGHTS element and the constituent elements that comprise a FLIGHTS record and so on. Where is the schema that defines the database structure in general? What we need is a schema that says a TABLE has FIELD elements and CONSTRAINT elements and the FIELD element has a SQLTYPE element and it has such-and-such attributes. Once you have a standard XML schema that describes a SQL-99 compliant database, for example, you can create instance of that schema. Let's call it the SQL-99-XML-SCHEMA (in general you would use a guaranteed unique name such as a registered URL but you get the picture). Now what we can do is create an XML document that uses the SQL-99-XML-SCHEMA. The TABLE element would have a NAME attribute and in your case a TABLE element named FLIGHTS would exist. HUGE difference here. There is no "FLIGHTS" schema type, there is a "TABLE" schema type with a name attribute.
Anyway, the main point is that the schema being generated by XML Spy is entirely useless for the purpose you initially suggested. It's a specific schema that describes instances of XML documents tied to a fixed database schema. Unless everybody has a FLIGHTS database it's not really useful. It's extremely useful for a java application using, say, castor to map objects to XML and vice versa. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Hal Deadman Sent: Tuesday, February 04, 2003 4:44 PM To: [EMAIL PROTECTED] Subject: RE: [Middlegen-user] xml schema from middlegen? I just tried XML Spy 5 (release 3) and it generated a W3C XML Schema from a the database schema I picked. It doesn't appear to be very flexible or configurable and it doesn't infer xml schema constraints from the database constraints (although you can add them manually). I don't think you can configure datatype mappings or influence the structure of the schema (Russian doll vs. flat dtd style with named types) It also appears that the XML schema it generates captures the structure of the database tables but XML instance documents based on that schema would not be able to store multiple rows of data for the elements defined in the schema. This is what it came up with for the middlegen airline schema. <?xml version="1.0" encoding="UTF-8"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema";> <xs:element name="FLIGHTS"> <xs:complexType> <xs:sequence> <xs:element name="FLIGHT_ID" type="xs:decimal"/> <xs:element name="NAME"> <xs:simpleType> <xs:restriction base="xs:string"> <xs:maxLength value="32"/> </xs:restriction> </xs:simpleType> </xs:element> <xs:element name="DEPARTURE_UTC" type="xs:dateTime"/> <xs:element name="ARRIVAL_UTC" type="xs:dateTime"/> </xs:sequence> </xs:complexType> </xs:element> <xs:element name="PERSONS"> <xs:complexType> <xs:sequence> <xs:element name="PERSON_ID" type="xs:decimal"/> <xs:element name="FIRST_NAME"> <xs:simpleType> <xs:restriction base="xs:string"> <xs:maxLength value="32"/> </xs:restriction> </xs:simpleType> </xs:element> <xs:element name="LAST_NAME"> <xs:simpleType> <xs:restriction base="xs:string"> <xs:maxLength value="32"/> </xs:restriction> </xs:simpleType> </xs:element> </xs:sequence> </xs:complexType> </xs:element> <xs:element name="RESERVATIONS"> <xs:complexType> <xs:sequence> <xs:element name="RESERVATION_ID" type="xs:decimal"/> <xs:element name="PERSON_ID" type="xs:decimal"/> <xs:element name="FLIGHT_ID" type="xs:decimal"/> <xs:element name="REGISTRATION_UTC" type="xs:dateTime"/> <xs:element name="COMMENTARY"> <xs:simpleType> <xs:restriction base="xs:string"> <xs:maxLength value="200"/> </xs:restriction> </xs:simpleType> </xs:element> </xs:sequence> </xs:complexType> </xs:element> </xs:schema> > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED]]On Behalf Of Rod > Macpherson > Sent: Tuesday, February 04, 2003 4:44 PM > To: [EMAIL PROTECTED] > Subject: RE: [Middlegen-user] xml schema from middlegen? > > > It does and I have used it and it works fine on a small > schema. Here's the question: what XML schema is it > generating? Answer: XML Spy's proprietary database schema. We > really do need a standard for this. > > -----Original Message----- > From: Hal Deadman [mailto:[EMAIL PROTECTED]] > Sent: Tuesday, February 04, 2003 1:34 PM > To: [EMAIL PROTECTED] > Subject: RE: [Middlegen-user] xml schema from middlegen? > > > It looks like XML Spy 5 has support for "Generation of > DTD/Schema from database". Haven't tried it and don't own > that version of the product yet, but at least someone must > have a use for it. > > http://www.altova.com/matrix.html > Search for "Generation of DTD/Schema from database". > > > > -----Original Message----- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED]]On Behalf Of Hal > > Deadman > > Sent: Tuesday, February 04, 2003 2:45 PM > > To: [EMAIL PROTECTED] > > Subject: RE: [Middlegen-user] xml schema from middlegen? > > > > > > 1) This page > > (http://www.xml.com/pub/a/2000/11/29/schemas/part1.html?page=6) > > describes how to model relations, although I am not an expert. It > > appears that you would use the <xsd:key/> and <xsd:keyref/> > to define > > a pk type > > constraint and an then refer to that constraint (fk-type > > constraint). They refer to elements via xpath and keyref refers to a > > key via the key's name. > > > > 2) http://www.w3.org/XML/Schema is the standard. This is > the standard > > that is replacing DTDs. It's not necessarily meant to replace data > > models but there are many similarities between XML schemas and a > > database schema. You > > can enforce things in XML schema such as uniqueness, > > relationships, data > > types, constrained datatypes, etc that you couldn't do in > > DTDs. I believe > > J2EE 1.4 describes all of it's XML files (ejb-jar deployment > > descriptors) > > using XML schema instead of DTDs. > > > > 3) The reasons I was interested were because I need to provide XML > > schemas that map closely to a database table for use with a JCA > > adapter to a database in an XML based workflow tool. > > > > I also saw a proposal from BEA for XMLBeans that takes an > XML schema > > and generates XML schema aware and constrained java objects. Wasn't > > planning to use that but I thought it might be another reason to > > want to quickly generate an XML schema. > > http://www.javaskyline.com/20030127_bea.html > > http://workshop.bea.com/xmlbeans/XsdUpload.jsp > > > > On the XML schema home page, there is a big list of tools that work > > with XML schemas, but I didn't notice any that help generate them > > (from anything > > other than DTDs). One example is Castor, which is described > > as: "Castor > > provides the only open-source Schema Object Model that loads > > your XML Schema > > in a Java representation. It also generates Java classes > > given an XML Schema > > and performs validation." Not being a Castor user, I don't > > know if they > > would benefit from having an XML schema generated for them or not. > > > > I looked into Torque which is a sub-project of Turbine on Jakarta. > > They generate an "XML schema" from a database but it's not the > > standard XML schema, rather it is a representation of a database the > > schema in their own > > XML format. > > > > XML Schema is supposed to be a big part of Microsoft Office > 11, maybe > > being able to create schemas from existing data models would be > > useful there, although maybe Microsoft supports that. I don't know. > > http://www.microsoft.com/presspass/features/2002/nov02/11-12XM > > LOffice.asp > > > > I don't really know how useful this would be for people and > it may not > > make sense. I am about to start a project where I will get some > > exposure to XML schema. As I learn more about XML schema, I will > > keep Middlegen in mind and > > see if I think it would be useful. > > > > Hal > > > > > -----Original Message----- > > > From: [EMAIL PROTECTED] > > > [mailto:[EMAIL PROTECTED]]On > > Behalf Of Aslak > > > Helles�y > > > Sent: Tuesday, February 04, 2003 1:47 PM > > > To: [EMAIL PROTECTED] > > > Subject: RE: [Middlegen-user] xml schema from middlegen? > > > > > > > > > 3 questions: > > > > > > 1) How would you model relations? Using ids? > > > 2) Is there any kind of standard for this kind of schemas? > > > 3) Who else than you would need this? > > > > > > Aslak > > > > > > > -----Original Message----- > > > > From: [EMAIL PROTECTED] > > > > [mailto:[EMAIL PROTECTED]]On > > Behalf Of Hal > > > > Deadman > > > > Sent: 4. februar 2003 19:40 > > > > To: [EMAIL PROTECTED] > > > > Subject: [Middlegen-user] xml schema from middlegen? > > > > > > > > > > > > I have run across a couple cases where it would be nice to > > > have a W3C XML > > > > Schema that mirrors an existing database schema. Are there > > > any tools out > > > > there that do that? Would that make sense as a > middlegen plug-in > > > > or at all? It wouldn't make use of Xdoclet but the information > > > > that > > > Middlegen has > > > > regarding the tables, columns, and relationships would be used. > > > > > > > > One thing that wouldn't be typical of a Middlgen > plug-in is that > > > > there would be one velocity template to generate the entire XML > > > > schema for the set of DB > > > > tables rather than one template that gets executed for > each table. > > > > > > > > I suppose there would have to be some mappings established > > > between XML > > > > datatypes and JDBC datatypes and this information would > need to be > > > > available in the template. > > > > > > > > I haven't worked much with XML Schema so most of what I > > > know is based on > > > > this article: > > > > > > > http://www.xml.com/pub/a/2000/11/29/schemas/part1.html?page=1 > > > The article > > > > talks about unique indexes and pk/fk type xml schema > equivalents > > > > on page 6. > > > > > > > > Below is an example of what a schema might look like for a > > > single table. > > > > > > > > If you had a table like this: > > > > CREATE TABLE COMPANY ( > > > > COMPANY_ID NUMBER, > > > > COMPANY_NAME VARCHAR2 (100), > > > > TICKER VARCHAR2 (20), > > > > MODIFIED_DATE DATE, > > > > CREATED_DATE DATE) > > > > > > > > You could create a velocity template that generated a > > > schema like this: > > > > > > > > <?xml version="1.0" encoding="UTF-8"?> > > > > <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"; > > > > elementFormDefault="qualified"> > > > > <xsd:simpleType name="companyNameType"> > > > > <xsd:restriction base="xsd:string"> > > > > <xsd:maxLength value="100"/> > > > > </xsd:restriction> > > > > </xsd:simpleType> > > > > <xsd:simpleType name="tickerType"> > > > > <xsd:restriction base="xsd:string"> > > > > <xsd:maxLength value="20"/> > > > > </xsd:restriction> > > > > </xsd:simpleType> > > > > <xsd:complexType name="companyType"> > > > > <xsd:sequence> > > > > <xsd:element name="company_id" type="xsd:integer"/> > > > > <xsd:element name="company_name" type="companyNameType"/> > > > > <xsd:element name="ticker" type="tickerType"/> > > > > <xsd:element name="modified_date" type="xsd:date"/> > > > > <xsd:element name="created_date" type="xsd:date"/> > > > > </xsd:sequence> > > > > </xsd:complexType> > > > > <xsd:complexType name="companyListType"> > > > > <xsd:sequence> > > > > <xsd:element name="company" type="companyType" > minOccurs="0" > > > > maxOccurs="unbounded"/> > > > > </xsd:sequence> > > > > </xsd:complexType> > > > > <xsd:element name="companies" type="companyListType"/> > > > > </xsd:schema> > > > > > > > > > > > > > > > > ------------------------------------------------------- > > > > This SF.NET email is sponsored by: > > > > SourceForge Enterprise Edition + IBM + LinuxWorld = > > Something 2 See! > > > > http://www.vasoftware.com > > > > _______________________________________________ > > > > middlegen-user mailing list [EMAIL PROTECTED] > > > > https://lists.sourceforge.net/lists/listinfo/middlegen-user > > > > > > > > > ------------------------------------------------------- > > > This SF.NET email is sponsored by: > > > SourceForge Enterprise Edition + IBM + LinuxWorld = > Something 2 See! > > > http://www.vasoftware.com > > > _______________________________________________ > > > middlegen-user mailing list [EMAIL PROTECTED] > > > https://lists.sourceforge.net/lists/listinfo/middlegen-user > > > > > > > > ------------------------------------------------------- > > This SF.NET email is sponsored by: > > SourceForge Enterprise Edition + IBM + LinuxWorld =omething 2 See! > > http://www.vasoftware.com > > _______________________________________________ > > middlegen-user mailing list [EMAIL PROTECTED] > > https://lists.sourceforge.net/lists/listinfo/middlegen-user > > > > ------------------------------------------------------- > This SF.NET email is sponsored by: > SourceForge Enterprise Edition + IBM + LinuxWorld =omething 2 See! > http://www.vasoftware.com > _______________________________________________ > middlegen-user mailing list [EMAIL PROTECTED] > https://lists.sourceforge.net/lists/listinfo/middlegen-user > > > ------------------------------------------------------- > This SF.NET email is sponsored by: > SourceForge Enterprise Edition + IBM + LinuxWorld =omething 2 See! > http://www.vasoftware.com > _______________________________________________ > middlegen-user mailing list [EMAIL PROTECTED] > https://lists.sourceforge.net/lists/listinfo/middlegen-user ------------------------------------------------------- This SF.NET email is sponsored by: SourceForge Enterprise Edition + IBM + LinuxWorld = Something 2 See! http://www.vasoftware.com _______________________________________________ middlegen-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/middlegen-user
